Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

• Scheme 50, involves single-electron reduction of the halomethane at the cathode, generating a halomethyl radical and a corresponding halide ion. The halomethyl radical is then captured by the acrylamide, leading to intramolecular radical cyclization. Final oxidation and deprotonation steps afford the

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• ) greater electrophilicity of the halo compound due to better leaving group ability of the halide ion, (iii) reduced toxicity, presumably due to faster hydrolysis [18], and (iv) easier oxidation of the halide to molecular halogen (E0 = 1.087 V (SHE) for Br2/Br−; E0 = 1.358 V (SHE) for Cl2/Cl−) [19

• redox couple NaBr–NaBrO3 in acidic media [40][41]. Other variations include the system KBr–Oxone® [42]. However, based on a literature review, we concluded that unparalleled efficiency and sustainability can be achieved through the well-established redox equilibria between hydrogen peroxide and halide

• ion in aqueous acidic media (Equation 1) [43]. Its practical implementation is surprisingly simple as standard aqueous HBr and H2O2 solutions are effective. The generated bromine can be involved in different chemical mechanisms, such as an Ar-SE (Equation 2) [44] or a radical substitution on activated

Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates

• Xing Liu,
• Wenjing Shi,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143

• ylide B. Thirdly, the intermediate C is formed by the nucleophilic substitution of a halide ion in substrate 1 by the allylic ylide B. Then, Michael addition of the amino group to the C=C bond results in the cyclic intermediate D. Finally, the spiro[indoline-3,5'-[1,2]diazepine] 3 is produced by the

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• successfully obtained from the reaction medium (Scheme 4). The proposed mechanism proceeded via cine-substitution. The rate-determining step was found to be the nucleophilic attack of the halide ion at the C-2 position of the O-tosylated imidazole 1-oxide. In spite of the difference in rate for the cases of

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

• , the in situ generated α-iodoketone was proposed to be the key active species. Keywords: 2-aminothiazoles; electrosynthesis; indirect electrolysis; halide ion; Introduction Thiazoles are prevalent structural motifs in a wide range of natural products [1] and synthetic molecules possessing various

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• -3-yl) phosphate 2 is activated by protonation with a haloid acid. Subsequently the phosphate leaving group is eliminated to generate the carbocation intermediate III, which is then followed by rapid combination with a nucleophilic halide ion to form a 3-monohalooxindoles 3 or 4. Conclusion In

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• , Br, Scheme 63) [114]. In this transformation, BX3 played a dual role as both a Lewis acid catalyst and a source of the halide ion nucleophile. This reaction resulted in the generation of the trifluoromethyl ketones 145 and halodifluoromethyl ketones 146 and 147 in high yields. As in the previous

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• (96% ee) despite using the same procedure as for the reaction between (S)-(+)-5 and PBr3. In addition, bromination of (S)-(+)-5 under Appel reaction conditions employing tetrabromomethane (CBr4) as a halide ion source used along with triphenylphosphine (Ph3P) was also investigated. Although this

Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with secondary amine nucleophiles

• Dingqiao Yang,
• Ping Hu,
• Yuhua Long,
• Yujuan Wu,
• Heping Zeng,
• Hui Wang and
• Xiongjun Zuo

Beilstein J. Org. Chem. 2009, 5, No. 53, doi:10.3762/bjoc.5.53

• also found that the halide ions might play an important role in transition metal-catalyzed ARO reactions, in which the reactivity and enantioselectivity could be significantly improved by choosing a suitable halide ion. It was found that the reaction yields and enantioselectivities increased in the

• order of Fhalide ion additives (Table 3, entry 1). Therefore, simply changing the halide ligand on the iridium catalyst from chloride to iodide or bromide leads to improvements in